The effect of renal calcium excretion on bone mineral metabolism of postmenopausal women in Korea / 대한내과학회지

ABSTRACT

BACKGROUND: Although all postmenopausal women are estrogen deficient, women who have postmenopausal osteoporosis may have some defects, in addition to estrogen deficiency, that explain for their higher rates of bone resorption and greater bone loss, relative to those who do not. To test the hypothesis that one of the defects is an impairment in renal calcium conservation, we have investigated relationship between urinary calcium excretion and bone mineral metabolism of postmenopausal women in Korea. METHODS: We have measured 24-hour urinary calcium level; serum osteocalcin level, serum alkaline phosphatase level; urine deoxypyridinoline level; and bone mineral density in 224 early postmenopausal, 158 late postmenopausal and 145 premenopausal women. RESULTS: 33.0 percent (74/224) of early postmenopausal women in Korea had urinary calcium excretion exceeding 4 mg/kg per day. The early postmenopausal women had higher (p < 0.05) values for mean urinary calcium to creatinine ratio of 0.241+/-0.008 mg/mg of creatinine vs. 0.209+/-0.010 mg/mg of creatinine and higher (p < 0.001) mean serum calcium level of 9.15+/-0.02 mg/dL vs. 8.92+/-0.03 mg/dL than the premenopausal women. Hypercalciuric group of early postmenopausal women had higher (p < 0.05) values for mean urine deoxypyridinoline level (8.6+/-0.4 nMol/mMol Vs. 7.7+/-0.2 nMol/mMol), higher (p < 0.05) mean serum alkaline phosphatase level (73.4+/-2.3 U/L Vs. 67.7+/-1.4 U/L) and lower (p < 0.05) mean bone mineral density of femur neck (0.785+/-0.012 g/cm2 Vs. 0.815+/-0.008 g/cm2) than the normocalciuric group. CONCLUSION: The early postmenopausal women had larger numbers of hypercalciuric women and higher values for urinary calcium excretion than the premenopausal women. Hypercalciuric group of early postmenopausal women had higher values for biochemical markers of bone turnover and lower bone mineral density of femur neck than the normocalciuric group. We suggest that hypercalciuria could be accounted for the partial cause of postmenopausal osteoporosis, but further studies are needed to elucidate the direct effect about that.